Recent advances in recombinant protein technology and better understanding of disease mechanisms have led to increases in the number and diversity of protein therapeutics. In this dissertation, we explore the controlled delivery of two HIV therapeutic proteins – interleukin-7 (IL-7) and 5P12RANTES.
HIV infections result in the depletion of CD4+ T-cells and a loss of naïve CD4+ and CD8+ T-cells. IL-7 is a critical cytokine involved in homeostatic expansion of naïve T-cells in lymphopenic hosts. In clinical trials, repeated injections of IL-7 boost both CD4+ and CD8+ cell counts. Daily injections, however, are painful and provide a route for pathogen entry. We developed a microparticle controlled release system to administer IL-7 in which a single injection can provide therapeutic delivery of IL-7. These microparticles showed effective delivery of IL-7 both in vivo and in vitro. Controlled release of IL-7 in mice demonstrated good biological activity in CD4+ and CD8+ T-cells, consistent with previously reported results using daily injections. Overall, IL-7 delivery using microparticles showed potential in vivo and further optimization will allow for evaluation of IL-7 as a potential HIV vaccine adjuvant.
5P12RANTES is a HIV entry blocker that has shown potential in macaque trials. However, 5P12RANTES’ potential as a long-term HIV preventive has not been explored partially due to the lack of sustained delivery systems. Affinity-based drug delivery systems utilize reversible interactions between the drug and the delivery system to control release. Using Surface Plasmon Resonance, we examined the strength of affinity interaction between 5P12RANTES and two classes of molecules – glycosaminoglycans and oligopeptides (active site of a chemokine receptor). These GAGs and oligopeptides were incorporated into hydrogels for controlled release. Release studies from these gels found that 5P12RANTES release corresponded to the strength of interactions. Gels containing molecules with stronger affinity to 5P12RANTES resulted in less burst and more sustained release. These delivery systems did not negatively affect the 512RANTES activity and released aliquots demonstrated good biological function after 30 days of incubation and release. The development of 5P12RANTES delivery systems described in this dissertation will allow for in vivo evaluation of 5P12RANTES as a long term HIV preventative.